Synthesis, Structure, and Magnetic Study of two Two-Dimensional 63

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DOI: 10.1021/cg100145e

Synthesis, Structure, and Magnetic Study of two Two-Dimensional 63 Honeycomb-Shaped and 44 Grid-Like Coordination Polymetic Networks Based on Hexa- and Dodecanuclear Manganese Cluster Units

2010, Vol. 10 2661–2667

Dan Liu, Qi Zhou, Yan Chen, Fen Yang, Yang Yu, Zhan Shi,* and Shouhua Feng State Key Laboratory of Inorganic Synthesis & Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China Received January 30, 2010; Revised Manuscript Received March 4, 2010

ABSTRACT: Two 2D coordination polymetic networks compounds of [Na3MnIII6(μ6-O)(thme)4(PhCO2)6(H2O)] 3 OH (1) and [NaMnIII4MnII8O2(thme)4(N3)(OAc)8(AcOH)2(CH3O)4] (2) with 1,1,1-tris(hydroxymethyl)-methane (H3thme) as the ligand have been synthesized and structurally characterized by X-ray diffraction, IR spectra, and elemental analyses, where the homovalence hexanuclear Mn cluster in compound 1 and the mixed-valence dodecanuclear Mn cluster in compound 2 acted respectively as network nodes in the formation of honeycomb-shaped and rhombic grid-like layer structures. In addition, magnetic studies of 1 reveal that antiferromagnetically coupled paramagnetic cluster behavior is operative within the hexameric Mn6 cluster and 2 exhibits antiferromagnetic coupling interactions and interesting frequency dependent in-phase as well as outof-phase susceptibility signals are observed, respectively.

Introduction Construction and characterization of coordination polymers in the field of supramolecular chemistry and crystal engineering has attracted significant interest, not only because of their interesting molecular topologies, but also because of their potential applications as functional materials.1,2 Up to now, there has been much progress in the discovery of polynuclear paramagnetic clusters (PMCs) such as Cu, Co, Fe, Ni, 3d-4f3 as decorating units to design new coordination polymer frameworks; however, there are only a few examples using manganese clusters as the building blocks to construct complicated and enchanting architectures.4,5 On the other hand, much more reported manganese polynuclearities as lowdimensional single-molecule magnets (SMMs) are known today.6,7 To build novel coordination polymers architectures with interesting magnetic properties, researchers have recently focused their attention on assembling SMMs as the available building blocks into multidimensional network systems incorporating either covalent or noncovalent interactions,8 mainly because SMMs have a large spin ground state together with a strong uniaxial anisotropy, which leads to a slow relaxation of their magnetization. In the design of fascinating structures using SMMs building blocks, one of the advantages is that anisotropy capable of holding the direction of magnetization can be tuned to create a hard magnet with a relatively large coercivity. These breakthroughs may open new perspectives on the design of new magnetic materials and create more complicated and enchanting architectures. 1,1,1-Tris(hydroxymethyl)-methane (H3thme), a preferred flexible tripodal alcohol linking the paramagnetic metals together in triangular arrays, has been recently utilized to synthesize some low-dimensional 3d transition metal SMMs.9 However, a formidable challenge is to use these well-known SMMs as decorating units to design new coordination polymer frameworks, which can have a higher number of outward-connecting sites

and a larger surface, and so far, the successful representative example is [MnIII2MnII2(hmp)4(OH)2MnII(dcn)6] 3 2MeCN 3 2THF (Hhmp = hydroxymethylpyridine; Hdcn = dicyanamine) reported by Miyasaka, Clerac, and co-workers.10 The exchange interaction between the well-known Mn411 building block and the isolated MnII ion via the dcn linker is very weakly antiferromagnetic. Nevertheless, this result shows that even with such a very small interaction in three-dimensional (3D) networks, it is possible to yield long-range order in the SMMs network. Additionally, azido-bridged compounds including a few SMMs from the [Mn4] core to the giant [Mn32] cluster have been structurally and magnetically characterized previously.12,13 Meanwhile, considering the two-dimensional (2D) extended networks with polynuclear manganese clusters as decorated nodes is still lacking,14 we have been particularly interested to introduce novel or known complexes based on higher-nuclear manganese clusters with fascinating structures and unusual magnetic behaviors into the coordination polymer chemistry. In this paper, we report in detail the synthesis, structures, and magnetic properties of compound [Na3MnIII6(μ6-O)(thme)4(PhCO2)6(H2O)] 3 OH (1) which represents a 2D hexagonal network based on a rare homovalent Lindquist-shaped hexanuclear manganese fragment, and compound [NaMnIII4MnII 8O2(thme)4(N3)(OAc)8(AcOH)2(CH3O)4] (2), in which EEazide has been used to bridge discrete polynulearity valencesandwich-type repeating units with the H3thme ligand in a stepwise manner to form a 2D infinite rhombic grid-like mixedvalence polymer. Experimental Section

*To whom correspondence should be addressed. E-mail: [email protected]. edu.cn. Phone: þ86-431-85168662. Fax: þ86-431-85168624.

Materials and General Methods. All chemicals were commercially purchased and used without further purification. The starting material [Mn3O(PhCO2)6(py)3(H2O)] for the reaction was synthesized by the method reported in the literature.15 Caution! Azide complexes are potentially explosive and should be handled carefully. The IR spectra were recorded in the range 400-4000 cm-1 with a Bruker 18174f FT/IR spectrophotometer by using KBr pellets. Elemental analyses (C, H, and N) were performed with a

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Results and Discussion Synthesis. The reaction of [Mn3O(PhCO2)6(py)3(H2O)] (3) (where py = pyridyl) with H3thme and NaN3 in a 1:1.5:2 ratio in acetonitrile gave a dark brown solution from which a hexanuclear cage [Na3MnIII6(μ6-O)(thme)4(PhCO2)6(H2O)] 3 OH (1) crystallizes in 55% yield after one week. When the same reaction was performed in methanol with Mn(OAc)2 3 4H2O instead of 3, we obtained the dodecanuclear complex 2. When we have tried to use 1 instead of Mn(OAc)2 3 4H2O as starting materials under different organic solvents - acetonitrile, ethanol, and dichloromethane at room temperature or high temperature and pressure solvothermal conditions, however, those efforts failed. Crystal Structure of 1. Single crystal X-ray diffraction reveals that compound 1 crystallizes in the trigonal space group R3, which is consistent with the XRPD experiment

Table 1. Crystal Data and Structure Refinement for 1 and 2a compound

1

2

chemical formula formula weight T (K) λ (A˚) space group unit cell dimensions

C62H69Na3Mn6O29 1676.78 293(2) 0.71073 R3 a = 18.663(3) A˚ b = 18.663(3) A˚ c = 35.810(7) A˚ γ = 120° 10802(3) 6 1.547 1.120 4132 0.0631 0.0674 0.1458 1.050

C44H80O38Mn12N3Na 1941.38 293(2) 0.71073 C2/c a = 25.7831(16) A˚ b = 13.5163(7) A˚ c = 22.1308(10) A˚ β = 104.520(5)° 7466.1(7) 4 1.727 2.047 9253 0.0566 0.0551 0.1492 1.070

V (A˚3) Z Dc [g 3 cm-3] μ [mm-1] reflns collected Rint R1 [I > 2σ(I)] wR (all data) goodness of fit

a Note: R1 = Σ Fo| - |Fc /Σ|Fo|; wR2 = {Σ[w(Fo2 - Fc2)2]/Σ[w(Fo2)]2}1/2; w = 1/[σ2|Fo|2 þ (0.0511P)2 þ 19.56P], where P = [|Fo|2 þ 2|Fc|2]/3.

)

Pekin-Elmer 2400 CHN Elemental analyzer. Mn was determined with a Leaman inductively coupled plasma (ICP) spectrometer. Thermogravimetric analysis was performed with a Perkin-Elmer TGA7 instrument in flowing N2 with a heating rate of 10 °C min-1. X-ray powder diffraction (XRPD) collected with a RAXIS-RAPID diffractometer equipped with graphite-monochromatized Mo KR radiation (λ = 0.71073 A˚) at 50 kV and 180 mA. Variabletemperature magnetic susceptibility data were obtained with a SQUID magnetometer (Quantum Design, MPMS-5) in the temperature range 2-300 K by using an applied field of 1 kG. The sample was embedded in solid eicosane to prevent torquing. Alternating current magnetic susceptibility measurements were performed in an oscillating ac field of 3.0 G and a zero dc field. The oscillation frequencies were in the 10-1000 Hz range. Pascal’s constants were used to estimate the diamagnetic corrections, which were subtracted from the experimental susceptibility to give the molar paramagnetic susceptibility (χm). Synthesis of [Na3MnIII6(μ6-O)(thme)4(PhCO2)6(H2O)] 3 OH (1). A mixture of [Mn3O(PhCO2)6(py)3(H2O)] (0.45 mmol, 0.50 g), H3thme (0.7 mmol, 0.084 g), and NaN3 (1 mmol, 0.065 g) in MeCN (15 mL) was stirred for 48 h to form a deep-brown solution. Dark black block-shaped crystals of 1 in 55% yield were collected, washed with Et2O, and dried at room temperature. Anal. Calcd for C62H69Na3Mn6O29: C, 44.37; H, 4.12. found: C, 44.29; H, 4.17. IR data (KBr disk, cm-1): 3419 (w), 2858 (w), 1601 (s), 1359 (vs), 1035 (w), 722 (w), 627 (m). Synthesis of [NaMn III4 MnII 8O 2(thme)4(N 3)(OAc)8(AcOH)2 (CH3O)4] (2). The same reaction was performed in methanol with Mn(OAc)2 3 4H2O (3 mmol, 0.735 g) in the presence of NEt3 (3 mmol, 0.42 mL) instead of [Mn3O(PhCO2)6(py)3(H2O)]. Brownred block-shaped crystals of 2 suitable for X-ray diffraction were isolated in 68% yield. Anal. Calcd for C44H80O38N3Mn12N3Na: C, 27.19; H, 4.12; N, 2.16; found: C, 26.98; H, 4.15; N, 2.12. IR data (KBr disk, cm-1): 3396 (w), 2900 (w), 2087 vs, 1567 vs, 1423 m, 1029 s, 578 m. X-ray Crystallography Determinations. Single crystal analyses were performed on the RAXIS-RAPID diffractometer equipped with graphite-monochromatized Mo KR radiation (λ = 0.71073 A˚) at 293 K for 1 and 2. All data were collected for absorption by semiempirical method using the SADABS program. The program SAINT was applied for integration of the diffraction profiles. Data analyses were carried out with the program XPREP. The structures were solved with the direct method using SHELXS-97 followed by structure refinement on F2 with the program SHELXL-97.16 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms of organic ligands, water, AcOH, and hydroxide groups were generated theoretically onto the specific carbon atoms and oxygen atoms, and refined isotropically with fixed thermal factors. CCDC744131 (1) and CCDC-744132 (2) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.ac.uk/data_request/cif. Crystal data and experimental details are summarized in Table 1; selected bond lengths for two complexes 1 and 2 are listed in Table 2.

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Table 2. Selected Bond Lengths [A˚] for 1 and 2a Complex 1 Mn1-O(5)#1 Mn1-O(2) Mn1-O(5) Mn1-O(3) Mn1-O(6) Mn1-O(1)

2.003(3) 2.004(3) 2.009(3) 2.013(3) 2.104(3) 2.374(3)

Mn2-O(4) Mn2-O(3) #1 Mn2-O(8) Mn2-O(4) #1 Mn2-O(2) Mn2-O(1)

1.967(3) 1.998(3) 1.998(3) 2.020(2) 2.031(3) 2.135(3)

Complex 2 Mn(1)-O(1) Mn(1)-N(1) Mn(1)-O(3) Mn(1)-O(2) Mn(1)-O(9) Mn(1)-O(5) Mn(3)-O(11) Mn(3)-O(6) Mn(3)-O(2) Mn(3)-O(19)#1 Mn(3)-O(5) Mn(4)-O(15) Mn(5)-O(10) Mn(5)-O(7) Mn(5)-O(19) Mn(6)-O(6) Mn(6)-O(15) Mn(6)-O(8)#1 Mn(6)-O(15)#1 Mn(6)-O(10)#1 Mn(6)-O(7)

2.134(4) 2.140(5) 2.151(3) 2.222(3) 2.229(3) 2.414(3) 2.080(4) 2.087(3) 2.094(3) 2.167(3) 2.316(3) 2.410(2) 2.223(3) 2.233(3) 2.318(3) 1.914(3) 1.929(2) 1.916(3) 1.930(3) 2.302(3) 2.317(3)

Mn(2)-O(9) Mn(2)-O(5) Mn(2)-O(7) Mn(2)-O(10) Mn(2)-O(13) Mn(2)-O(15) Mn(4)-O(8) Mn(4)-O(4) Mn(4)-O(17)#1 Mn(4)-O(2) Mn(4)-O(9) Mn(5)-O(14) Mn(5)-O(17) Mn(5)-O(18) Mn(5)-O(16)

1.914(3) 1.925(3) 1.937(3) 1.957(3) 2.129(3) 2.291(2) 2.103(3) 2.116(3) 2.136(3) 2.142(3) 2.311(3) 2.181(3) 2.233(3) 2.317(4) 2.441(4)

Na(1)-O(14) Na(1)-O(16)#2 Na(1)-O(16) Na(1)-O(18) Na(1)-O(18)#2

2.277(3) 2.512(4) 2.512(4) 2.544(4) 2.544(4)

a Symmetry transformations used to generate equivalent atoms: for 1: #1 -x þ y þ 1, -x þ 1, z; for 2: #1-x, -y, -z; #2 -x, -y þ 1, -z.

(Figure S3 in the Supporting Information). The crystal structure of 1 reveals a 2D extended structure based on homovalent hexanuclear clusters similar to the first reported mixed-valent hexanuclear manganese clusters.17 The structure of the manganese-oxygen core of 1 (Figure 1a,b), which is the same as Lindqvist anion [M6O19]n-, can be described as an octahedron. In the Mn6 octahedral cluster, there are six terminal oxo-groups from six PhCO2- anions, 12 doubly bridging oxo-groups from four thme3- anions, and one μ6oxo-group at the center of the cluster. The triangular faces and vertexes of this octahedron are occupied by bridging thme3- and PhCO2- ligands, respectively. All manganese ions are in a pseudo-octahedral environment, and their

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Figure 1. The structure of compound 1: (a) Local coordination environment for MnIII ions. (b) View of the polyhedral and ball-and-stick of the homovalent Lindquist-shaped μ6-oxo-centered [Na3MnIII6(μ6-O)(thme)4(PhCO2)6]þ cation SBU. (c) 2D network structure (Mn and Na atoms are drawn as polyhedrons). (d) The topological structure of the 2D (6, 3) hexagonal networks. (Hexanuclear Mn(III) cluster is shown in magenta spheres, and yellow sticks represent Na ions.)

oxidation state has been assigned based on the presence of Jahn-Teller (JT) axial elongations and by bond valence sum (BVS) calculations (Table S1 in the Supporting Information). Although the JT axes are not parallel, there is also a net contribution of anisotropy from single MnIII ions. Three Naþ counterions and one water molecule are found in the crystal lattice. The coordination environments around the sodium ions are six-coordinated, with three alkoxide O atoms from three thme3- ligands, two O atoms from two PhCO2- anions, and one hydrate molecule. Each Mn6 aggregate is connected through three Naþ ions mediated three hydrate molecules, resulting in a 2D infinite honeycombshaped coordination layer (Figure 1c). Up to now, there have been a few examples of discrete and polymeric aggregates of 3d metal clusters linked through alkali- or alkaline-earthmetal ions with an overall nuclearity to construct multidimensional coordination polymer.18 The shortest Mn 3 3 3 Mn separation between the Mn6 units is relatively large (9.937(1) A˚). The 2D layers stack along the c axis in an ABCABC sequence with mean interlayer separation of ∼10.7 A˚, such that the macrocyclic cavity does not form extended channels perpendicular to the 2D network. Compound 1 exhibits 2D honeycomb-shaped or hexagonal

networks, structural analogues of graphite (Figure 1d). Although close examples of 1 containing transition metal ions (such as Ag, Co, or Ni) are well documented,19 Mn6 is, to our knowledge, the first homovalence repeating unit like Lindqvist anion [M6O19]n- reported in honeycomb-shaped networks for a manganese coordination polymer. Crystal Structure of 2. Single crystal X-ray diffraction reveals that compound 2 crystallizes in the monoclinic space group C2/c, which is consistent with the XRPD experiment (Figure S3 in the Supporting Information). As seen in Figure 2a,b, the structure of the manganese-oxygen core of 2 built on a well-known Mn12 SMM was reported by Brechin, Christou, and co-workers,20 and it may be dissected into three layers with an ABA arrangement that looks like the valence-sandwich. Layer A consists of four MnII ions joined together by one azido ion, one μ-acetate and three deprotonated acetate groups, and two methoxo ligands in which only one adopts a typical μ3-bridging mode. Layer B consists of a central MnIII4 rhombus, in which all of the elongation JT axes of the MnIII ions are almost parallel to each other. Valence-sandwich-type layers A, B, and A are connected by two fully deprotonated μ2-OAc and four thme3- ligands in which each of them uses two arms to form

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Figure 2. The structure of compound 2: (a) View of the ball-and-stick of the valence-sandwich-type [MnIII4MnII8(O)2(thme)4(OAc)8(AcOH)2(CH3O)4] SBU. (b) Polyhedral of the SBU in the structure. (c) Polyhedral and ball-and-stick representation of the 2D structure. (d) View of the (4, 4) grid (pink balls representation of the mixed-valence [Mn12], blue, and yellow stick representation of Na ions and azido ligands, respectively).

μ3-OR bridges and the third arm acts as a μ2 bridge. Notably, only one Mn ion is seven-coordinated and the others Mn ions are six-coordinated, and two rare five-coordinated oxide ions are at the core center. The oxidation states of the Mn atoms and the protonation levels of the O2- and OH- were established by bond valence sum (BVS) calculations (Table S2 and Table S3 in the Supporting Information).21 Furthermore, each valence-sandwich-type [Mn12] cluster is then connected to four others via alkali-metal ions and azides ligands resulting in a 2D (4,4) grid framework (Figure 2c). It is of interest to note that a 1D zigzag chain is formed by linking the mix-valence Mn12 units through an end-to-end azide running along the c-axis (Figure S1 in the Supporting Information). However, to the best of our knowledge, it is only the second highest-nuclearity known where an azido has been used to bridge discrete large clusters in a stepwise manner to form a polymer. The first highest-nuclearity repeating unit Mn17 bridged by μ1,3-N3 ligands to form a 1D chain is the one developed by Christou.22 Thus, compound 2 exhibits a perfect rhombic-grid with rhombus dimensions of 14.55  13.52 A˚ represented by rhombic grid model (Figure 2d). Magnetic Properties. Variable-temperature DC magnetic susceptibilities measured for the two compounds are shown in Figure 3 in the form of χmT value versus T plots. The room temperature χmT values are 14.6 cm3 K mol-1 for 1 and 37.739 cm3 mol-1 K for 2, much lower than the spin-only values of 18 cm3 K mol-1 and 47 cm3 mol-1 K for the two compounds. The molar magnetic susceptibility χm follows the Curie-Weiss law for 1 with C = 17.10 cm3 K mol-1, and

a negative θ = -47.91 K above 160 K and for 2 with C = 41.48 cm3 K mol-1, and a negative θ = -34.49 K above 50 K (Figure S2 In the Supporting Information), which suggest the antiferromagnetic interactions within the hexanuclear Mn6 core and the dodecameric Mn12 core are operative. At lower temperature, the χmT decreases continuously in both cases indicating Zeeman effects, zero-field splitting, and perhaps weak intermolecular antiferromagnetic exchange interactions between the magnetic centers. Additionally, we found that the χmT value 37.739 cm3 mol-1 K for 2 is much higher than 31.4 cm3 mol-1 K of the well-known isolated Mn12 SMM at 300 K. This indicates that the antiferromagnetic exchange interaction within the 2D extend network compound 2 is stronger than the isolated Mn12 core. The diversity of magnetic properties between the isolated and interconnected cluster of 2 may be mainly due to the mode μ1,3-N3 bridged manganese clusters along the c-axis usually exhibiting stronger antiferromagnetic coupling. To analyze the observed magnetic data, the susceptibility data of 1 was simulated using a model that employed only two J values (Figure 3). The exchange interaction models are used for 1: one J1 between the MnIII ions interacts through one μ2-O atom from the thme3- ligands and one (J2) with each MnIII mediated by a μ6-O atom. Using the program MAGPACK23 and employing the Hamitonian in the equa^ = -2J1(S^1S^1A þ S^1S^2A þ S^1S^2B þ S^1S^1B þ S^1AS^2A þ tion H ^ ^ S 2AS 2B þ S^2BS^1B þ S^1AS^1B þ S^2S^2A þ S^2S^2B þ S^2S^1A þ S^2S^1B) -2J2(S^1S^2 þ S^1AS^2B þ S^1BS^2A), afforded the parameters J1 = -1.833 cm-1, J2 = -2.291 cm-1, g = 1.97, zJ0 = -0.012 cm-1, with the final agreement factor R = 5.03  10-5

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Figure 3. (a) Plot of χmT vs T for 1 and 2. The solid line represents a simulation of the data. (b) The exchange interaction models used for 1. Black-dotted line J1 and gray-dotted line J2.

Figure 4. Plot of reduced magnetization (M/NμB) versus H/T for 1 (a) and 2 (b) in the temperature range 2.0-10 K.

(R = Σ(χobs - χcald)2/Σ(χobs)2. But there is no significant enhancement from only J1, only J2 and J1 = J2. The small J values indicate that antiferromagnetic exchange interactions between manganese(III) ions mediated by oxygen atoms are relatively weak. Considering the cluster-cluster magnetic interactions via sodium ions-bridge connecting into a 2D honeycombshaped extended network, we have attempted to model the interactions by Heisenberg-Dirac-Van Vleck (HDVV), but we failed to obtain the ideal results because the augment variants in the formula would excessively enhance the fitting difficulty. For 2, given the size of the molecules, it is not possible to apply the Kambe24 method to determine the individual pairwise exchange interaction parameters between the Mn ions, and direct matrix diagonalization methods are also computationally unfeasible. Thus, to determine the spin ground states of complexes 1 and 2, magnetization data were collected in the temperature and magnetic field ranges of 2.0-10 K and 0.5-5 T, respectively. The nonsuperposition of the isofield lines for 1 (Figure 4a) is indicative of the presence of a significant ZFS. The data was fit using the ANISOFT,25 which assumes only the spin ground state of the

Mn6 unit is significantly populated. A good fit for 1 was obtained S = 3, g = 1.93, and D = -0.79 cm-1 (Figure 4a). Although the fitted data may not be reliable, this suggests appreciable magnetic anisotropies. On the other hand, we could not obtain a good fit for 2 data assuming that only the ground state is populated in this temperature range, suggesting that low-lying excited states are populated even at these low temperatures (Figure 4b). Further magnetic characterization of the two compounds were performed by field-dependent magnetization at T = 2 K. Figure 5a shows that there is a rapid increase in M-H at the start of lower field and magnetic moment then it continues to increase and does not saturate at the highest field measured for both compounds. A possible explanation is that there are low lying excited states of higher spin and that these become populated at higher field, hence preventing saturation. Thus, two compounds are soft magnets without nondetectable coercivity. Figure 5b shows that the critical field Hc = 700 G for 1 is approximately detected by the sharp peak of dM/dH vs H. This indicates that compound 1 shows

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Figure 5. (a) The magnetization (M) versus field (H) hysteresis loops for complexes 1 and 2. (b) The derivatives dM/dH of 1 at 2 K.

Figure 6. Temperature dependence of the in-phase (a) and out-of-phase (b) for 2 in a 3.0-G oscillating field at the indicated frequencies.

just magnetic behavior of a antiferromagnetically coupled paramagnetic cluster. The conclusions from the dc studies were also confirmed by alternating current (ac) susceptibility experiments. The ac magnetic susceptibilities for both 1 and 2 were collected in a zero-applied dc field with a 3.0 G ac field oscillating at frequencies 10-1000 Hz. A frequency-dependence increasing in the in-phase as well as out-of-phase susceptibility with decreasing temperature is observed for 2 (Figure 6). Although the out-of-phase ac susceptibility (χm00 ) value is lower, similar results also exist in some reported papers.20,26 However, we could not observe the maxima in the out-ofphase susceptibility signal due to the very fast relaxation of magnetization which ultimately shifts the maxima below 2.0 K; hence, further low-temperature measurements such as magnetization vs dc field scans on single crystals using a micro-SQUID are required to determine the anisotropic energy barrier for the reorientation. Furthermore, the dynamic susceptibility data for 1 showed no evidence of magnetic ordering or slow paramagnetic relaxation. Thermal Stabilities by TG. Figure S4 in the Supporting Information displays the first weight loss (calc, 8.15%; found, 7.93%) in 1 at about 89 °C, corresponding to coordi-

nation water and hydroxide molecules, which is followed by a strong exothermic peak at 248 °C where the decomposition of the host framework of 1 starts. The TG curve of 2 indicates two steps of weight loss. The first weight loss is 6.02% in the temperature range of 55-120 °C, corresponding to the loss of protonated methanol molecules as structural solvents (calc. 6.39% for four methanol molecules).The final weight loss of 55.82% (calc. 56.15%) between 200 and 350 °C represents the loss of eight protonated acetic acid molecules, two acetic acid molecules, one azide anion, and four H3thme ligands per [NaMnIII4MnII8O2(thme)4(N3)(OAc)8(AcOH)2(CH3O)4]. Therefore, the decomposition temperature for 2 was observed to be approximately 200 °C. Conclusion In summary, we have developed a rational synthetic strategy for desired architectures causing the construction of two interesting 2D extended networks composed of cluster-based SBUs. Toward this effort, complex 1 is the first example of utilizing an unprecedented homovalent Lindquist-shaped Mn6 repeating unit in 2D honeycomb-shaped networks for a manganese coordination polymetic network, while com-

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pound 2 appears to be the highest-nuclearity Mn12 as network nodes in the formation of a 2D grid-like layer structure. The discovery of these new molecule-based magnetism networks enriches our knowledge of structural topologies and may further demonstrate the great potential of using azido groups or other pseudohalide linkers in conjunction with Mnx clusters in multidimensional network systems. Work in this area is continuing in our group. Acknowledgment. This work was supported by the Foundation of the National Natural Science Foundation of China (Nos. 20671040, 20971054, and 90922034), New Century Excellent Talents in University, and the Key Project of Chinese Ministry of Education. Supporting Information Available: Crystallographic details in CIF format, BVS calculations (Tables S1-S3), zigzag chain along the c-axis for 2 (Figure S1), plots of χM-1 vs T (Figure S2), XRPD patterns (Figure S3), and TG curves (Figure S4). This material is available free of charge via the Internet at http://pubs.acs.org.

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